Antonio Padilla

Dr Antonio Padilla

Research Fellow

Organisation

University of Nottingham

Research summary

What is gravity? To Newton it was the force that caused the apple to fall to earth and held the planets in orbit around the Sun. To Einstein is was the curvature of space and time. To a particle physicist it is the exchange of a "virtual" called the graviton. To a modern day string theorist, it is the exchange of tiny loops of vibrating strings, within a sea of extra dimensions.

Although we know a lot about gravity, it remains the most mysterious of the fundamental forces, largely because it is so much weaker than the rest. But despite this feebleness, its long range and attractive nature guarantee that it dominates the Universe on the largest scales. My research is devoted to understanding this mysterious force at both the largest and the smallest scales.

Consider the smallest scales. This is the realm of quantum gravity, where Einstein's equations break down. If we can make sense of this then we essentially have the key to understanding our own existence. This is because the physics of the very very early Universe was dominated by quantum gravity, so if we can understand that, perhaps we can understand how the Universe began.

Now consider the largest scales. This is the dark realm, where dark energy and dark matter reign supreme. Dark energy, in particular, is a mysterious substance that causes the Universe to expand at an accelerated rate. Particle physics has failed miserably to explain what dark energy might be. Since its properties are inferred through gravity, perhaps we need to better understand how gravity behaves on the largest scales before we can make any real sense of dark energy. Is the acceleration of the Universe really just a signal that Einstein's theory of gravity breaks down on large scales? Was Einstein wrong?